The following 3GPP (3rd Generation Partnership Project) document shall be considered as relevant background art in the field of the invention:    [1] TS 22.146: “Multimedia Broadcast/Multicast Service; Stage 1”.    [2] TS 25.346 (Release 6): “Introduction of the Multimedia Broadcast Multicast Service (MBMS) in the Radio Access Network”.    [3] TR 23.846: “Multimedia Broadcast Multicast Service; Architecture and Functional Description”.    [4] TR 25.992: “Multimedia Broadcast Multicast Service (MBMS); UTRAN/GERAN Requirements”.    [5] R3-030464: “MBMS Service Scenarios”; 3GPP TSG-RAN3 Meeting #35. Seoul, Korea, 7-11Apr. 2003.
According to the MBMS protocols and channels described in these documents, the MBMS paradigm is based on the possibility to carry valuable content on multicast/broadcast radio channels in order to serve multiple users at the same time with the same data flow, therefore minimising the radio and network resources consumption. By means of the MBMS technique service contents are transferred in the downlink direction only: from the network to the UE (User Equipment).
Different UMTS Quality of Service (QoS) classes are defined in 3GPP document TS 23.107, namely: Conversational, Streaming, Interactive and Background. The only classes that are applicable to the MBMS transmissions are Streaming and Background, because they imply data transfer in the downlink direction only. Streaming and Background are very different traffic classes, and they imply very different kinds of transports. Streaming class is part of the Real Time (RT) services with guaranteed bandwidth, e.g.: audio-video streaming, where low transfer delay is not a very stringent requirement and buffering can occur in the UE. Background class is part of the Not Real Time (NRT) services and is delay insensitive, e.g.: file download, with the lowest priority and no guaranteed bandwidth.
MBMS service can be transmitted either through a ptp (point to point) channel or through a ptm (point to multipoint) channel. One channel for each user is engaged with ptp, while one channel for all the users in the cell is engaged for ptm. Non-tracking and tracking/counting areas are distinguished in standardisation. Non-tracking are high-concentration areas (e.g. stadiums) where the transmissions will be only ptm by configuration. In tracking/counting areas the MBMS users are tracked and/or counted before transmission, in order to know how many they are in each cell for a given service. Counting of the active users in tracking/counting areas allows to decide whether it's better to setup a ptm channel, a number of ptp channels or no channels. A switching threshold between ptp and ptm is established for this purpose, this might be around 8 users.